The method of slush molding plastisol or PVC powder or other materials is generally known and is described in the literature, of which the following examples can be cited:
1) "PLAST"--Sept. 1979 pp 175-177. PA1 2) "MODERN PLASTIC ENCYCLOPEDIA" 1977-1978 pp 340 onwards. PA1 3) BALL W., Ziebart W., Woite B. (BMW) Mannheim VDI conference "New Requirement for Car Interior Trim" pp 1-18. PA1 4) Pabst H. G., Shaper S., Schmidt H., Terveen A. (AUDI) Mannheim VDI Conference 1987--"Development and large-scale use of dashboards produced by Slush Molding PVC". PA1 5) Khue N. N., Kunpers-Martz M., Dankmeier O. (EVC) "Development of optimum powder-blend for slush molding" IVth International Conference PVC '90-24-26 April 1990, Brighton U. K., pp 31/1-31/14. PA1 a) molding a gasket which substantially reproduces as such or slightly modified the profile of the mold along a line thereof which defines on the molded article the corresponding separation line between two different colors, PA1 b) providing on the inside of the mold along the separation line at least one dividing wall to define two separated half spaces inside the mold, PA1 c) fixing the gasket onto the dividing wall in proximity to the mold to form a seal within the mold between the two half-spaces, PA1 d) slush molding a layer of a first material constituting the first of the two different colors, the layer adhering to the mold only on the walls of the first half-space defined within it, PA1 e) consolidating the layer of the first material adhering to the mold, PA1 f) removing the dividing wall and the relative gasket from the mold, PA1 g) slush molding a continuous layer of a second material constituting the second of the two or more colors, and repeating the process according to the number of colors required. PA1 In stage d) of the aforesaid method, the material is left in contact with the mold for the time required for it to adhere and partly gel or melt in the part relating to the first color. PA1 a) providing a mold having an inner surface; PA1 b) providing a gasket having a profile which is approximately the same as a profile of a corresponding region of the mold inner surface; PA1 c) providing rigid material inserts in the gasket; PA1 d) fixing the gasket to a separation wall having a chamber therein; PA1 e) inserting the gasket and the separation wall into the mold, and aligning the gasket along the corresponding region of the mold inner surface to create a seal between the mold inner surface and the separation wall and to define first and second half-spaces within the mold that are sealed from each other; PA1 f) compressing the gasket against the corresponding region of the mold utilizing a mechanical device; PA1 g) slush molding a layer of a first colored material within the first half-space, the layer of the first colored material only adhering to walls defining the first half-space; PA1 h) consolidating the layer of the first colored material; PA1 i) removing the gasket and the separation wall from the mold; PA1 j) slush molding a continuous layer of a second colored material within the mold, thereby producing the molded two-colored article which includes the layer of the first colored material, the continuous layer of the second colored material, and a separation line between the layer of the first colored material and the continuous layer of the second colored material.
FR-A-1,439,028 (Rhone Poulenc), CH-A-293,508 (J. Croning), FR-A-1,075,378 (Telegraph Construction), PA0 FR-A-1,381,850 (Gosudarstvenny), PA0 GB-A-905,546 (Plastomatic) PA0 U.S. Pa. No.-A-2,736,925 (J. S. Heisler), PA0 FR-A-1,131,153 (National Research), PA0 GB-A-1,337,962 (Aquitaine Total), PA0 GB-A-1,056,109 (Celanese), PA0 U.S. Pat. No.-A-3,039,146 (T. Hengel.), PA0 U.S. Pat. No.-A-2,915,788 (T. Hengel), PA0 GB-A-865,608 (T. Hengel), PA0 FR-A-916,055 (ICI), PA0 GB-A-1,025,493 (M. F. Smith), PA0 FR-A-1,560,675 (Goodyear Tire), PA0 DE-A-1,554,967 (Vaessen-Schemaker), PA0 IT-A-22197 A/80 (ILPEA), PA0 DE-A-3,417,727 (YMOS).
All these patents or articles describe a substantially similar process, briefly consisting of filling a preheated metal mold with polymer liquid or powder, removing the excess liquid or solid and then heating the mold to complete gelling or fusion of the material which has adhered to it. The mold is then cooled and the final molding extracted.
In the sector involving such articles, a problem has recently appeared when trying to obtain a finished product, such as simulated leather for trimming an automobile dashboard, having two or more sharply divided colors in the exposed part of the molding.